Question: In language class, the girl to boy ratio is $6$ to $9$. If there are a total of $75$ students, how many boys are there?
Answer: A ratio of $6$ girls to $9$ boys means that a set of $15$ students will have $6$ girls and $9$ boys. A class of $75$ students has $5$ sets of $15$ students. Because we know that there are $9$ boys in each set of $15$ students, the class must have $5$ groups of $9$ boys each. There is a total of $45$ boys in language class.